What this code means

The PCM has detected that the long-term fuel trim system correction has exceeded the rich limit. Similar to P1123 but applies to the overall system-level fuel trim rather than individual bank correction.

Symptoms

• Check Engine Light
• Poor fuel economy
• Black exhaust smoke
• Rich exhaust odor
• Rough idle

Common causes

• Multiple leaking fuel injectors
• Fuel pressure regulator failure
• EVAP system purging excessively
• Faulty MAP or MAF sensor over-reporting airflow
• Stuck-open fuel injector

Diagnostic steps

1. Monitor system-level fuel trim on scan tool
2. Compare bank-to-bank fuel trims
3. Check fuel pressure at idle and under load
4. Test EVAP purge valve for leaking
5. Inspect fuel injectors for leaks

Repair notes

Diagnose and repair the source of excess fuel delivery causing the rich system fuel trim.

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